Heretofore, various energy storage systems have been utilized to store energy from such sources as electrical, solar, wind, water, and the like. However, many such systems are bulky, heavy, or have a low current density, or low energy efficiency, or other drawbacks.
One type of prior art energy storage device is a zinc-chlorine cell or battery. Various United States patents on such a device include U.S. Pat. Nos. 3,713,888; 3,809,578; 3,814,630; 3,993,502; . 4,072,540; 4,127,701; . 4,162,351; and 4,206,269. In this type of device, one electrode is actually made out of zinc. The other electrode is generally a porous material. The electrolyte is generally zinc chloride and no semi-permeable membrane separates the two electrodes. Upon charging of the cell, zinc metal is actually plated out upon a negative electrode substrate with chlorine gas being evolved at the positive porous electrode. Many of the above-noted patents relate to the use of the zinc-chloride cell within an automobile and also to the collection and containment of the chlorine gas by freezing and forming a hydrate at a temperature of less than minus 5.degree. C.
U.S. Pat. No. 4,215,182 converts solar energy to chemical and electrical energy using a photoelectric-chemical membrane cell to regenerate the redox anolyte of a redox-oxygen cell. This patent is not pertinent in that it relates to three-phase electrodes, to teflon-bonded air diffusion cathodes, and to the use of oxygen, either venting it from the system or utilizing oxygen to combine with hydrogen to form water. Moreover, membrane 31 apparently is not an anionic membrane.
U.S. Pat. No. 4,192,910 to Frosch et al relates to a redox type cell having two compartments separated by a membrane. In one compartment a ferrous/ ferric couple exits in a chloride solution, whereas the other cell has a chromic/chromous couple in the chloride solution. Upon charging of the cell, a thin layer of lead is deposited onto the negative electrode. This patent lacks any suggestion of the utilization of a chlorine compartment and it is known to the art that ferric ions tend to foul or plug the membrane.
U.S. Pat. No. 4,159,366 to Thaller also relates to a rebalance redox cell utilizing a hydrogen gas feed for one electrode, an ion permeable membrane, and an anode chamber containing ferric or ferrous ions. Thus, the anode chamber contains a gas. It is stated that one of the problems with an iron-chrome cell is the chromous ion is a strong reducing agent and can reduce the hydrogen ions contained in the anode fluid to hydrogen gas which creates an imbalance in the system and a limiting factor on the capacity of the cell. Hence, the rebalance cell serves to return capacity to the iron-chrome cell by electroc-chemically combining the hydrogen gas with the excess ferric ions. This cell is not rechargeable, hence the patent is not pertinent.
U.S. Pat. No. 4,128,704 to McKinzie et al relates to a photochemical energy storage system in which a source of oxygen serves as a feed gas to one electrode. In all, the system actually contains four electrodes and does not utilize a membrane, nor does it relate to applicants' hybrid type cell and hence is not pertinent.
U.S. Pat. No. 4,018,971 to Sheibley et al relates to special gels made from silica powders and hydrochloric acid which are impregnated onto a polymeric foam, with the resultant sheet utilized in a semi-permeable anionic membrane which permits chloride ions to be transported therethrough. The various types of cell combinations include iron and titanium or iron and chrome. However, no suggestion is made as to the utilization of an electrode containing saturated chlorine gas therein and the elimination of iron following the membrane.
U.S. Pat. No. 3,909,297 to Zietner et al relates to a lithium-chlorine fuel cell having a porous graphite cathode. The lithium salt is contained as a eutectic mixture of potassium chloride and lithium chloride which melts at about 359.degree. C. and higher. The cell thus requires molten lithium which is continually oxidized in the molten electrolyte. Hence, this patent is not pertinent.
U.S. Pat. No. 3,540,933 to Boeke relates to a fuel cell combining at least two redox couple complexes of metallic elements having an equilibrium potential of not more than 0.8 volts apart from each other. Altough various types of cells are suggested, there is no suggestion of a chrome-chlorine cell and a ceramic membrane is utilized. It is further noted that this system relates to a once-passed through type system which amounts to a fuel cell as distinguished from a rechargeable redox system. Hence, it is not pertinent.
U.S. Pat. No. 3,540,934 also to Boek relates to a series of connected multiple redox cells by a non-conductive tubing having a ratio link to the inside tube diameter of at least 10 to 1. Hence, it is not pertinent.
U.S. Pat. No. 3,360,401 to Grasselli et al relates to a fuel cell wherein each electrode has a metal oxide coating thereon and wherein an intermediate electron transfer species is provided as a colloidal dispersion of a solid redox system in the electrolyte. The patent further relates to a gaseous oxidant reactant. Therefore, it is not pertinent.
U.S. Pat. No. 3,279,949 to Schaefer et al relates to a vanadium redox cell and hence is not pertinent.
U.S. Pat. No. 3,996,064 to Thaller relates to an electrochemical cell system containing switching means for applying a charging voltage from a source of non-continuous electrical power, for example solar energy, water level from a reservoir, and the like. The cell has a semi-permeable anion membrane, and basically relates to an iron-chrome type cell. Column 4 contains a statement that high oxidation-reduction potential should be avoided to permit hydrogen from being disassociated from the water and also possibly oxygen. No disclosure or suggestion is made to the use of an active anion electrolyte or of a dissolved neutral species, that is a dissolved gas-liquid phase system as in applicants' invention. Moreover, the iron usually fouls the membrane.
U.S. Pat. No. 4,129,683 relates to an anhydrous hydrogen-chlorine regenerative fuel cell and hence is not pertinent in that it does not contain any metal therein.
U.S. Pat. No. 4,320,179 relates to the purification of a halogen and an hydrohalic acid in electrochemical system through the utilization of a low halogen oxidation over voltage electrode in one compartment and a low halogen reduction over voltage electrode in a second compartment. Hence, this patent lacks any reference to the use of an electrolyte containing a metal therein.